Put shrimp in a saucepan and add water to cover.,Add allspice, garlic, peppercorns and salt.,Bring gradually to a boil.,______,Let stand until cool.,Peel and devein shrimp.,There should be about 4 cups.,To prepare sauce, put mustard and vinegar in a mixing bowl and add salt and pepper.,Beat with a wire whisk and gradually add oil, stirring constantly.,If you beat briskly enough, the oil should blend in smoothly without separating.,Stir in remaining ingredients for the sauce.,Put about half a cup or less of shredded lettuce on each of eight salad plates.,Arrange an equal number of shrimp on lettuce.,Spoon sauce to cover shrimp completely.,Serve with lemon wedges.